Sweatshirts, jackets, t-shirts all work for Alaska. If however, you are doing some glacier excursion, then possibly a warmer jacket will be required, but for going around town, etc...just dress in layers and peel off as needed, days start out cold and do tend to warm up. Don't forget to pack a pair of shorts, we went late in the season, first week in Sept., and had some afternoons in the 70's, so shorts were fine.